Automatic defibrillators use a pair of electrodes applied to the chest of the victim for sensing EKG (electrocardiograph) signals from the victim. These electrodes are also used to deliver a high voltage defibrillator pulse to the victim when electrocardiograph interpretation permits discharge, either by advising the rescuer to deliver the shock or by automatic delivery of the shock. Precordial compression in the area of the breastbone helps blood circulation and breathing. The rescuer is provided with a verbal warning such as “step back” prior to delivering the shock to protect the rescuer from a high voltage defibrillator shock. In the present invention we avoid the need for discontinuance of precordial compression by the rescuer, resulting in a better outcome of the rescue effort.
Applicants' previous patent application Ser. No. 09/217,008 filed Dec. 21,1998, describes a sheet of insulation material that can be applied to the victim to protect the rescuer from defibrillator shocks. While the rescuer is partially protected, it is found that the rescuer feels highly annoying moderate shocks when the patient is defibrillated. Apparatus that provides more complete insulation would be useful.
In our earlier U.S. Pat. No. 5,957,856 and patent application Ser. No. 09/385,537 filed Aug. 30, 1999, a system is provided for evaluating the likelihood that a defibrillator shock will successfully restore spontaneous circulation, based on analysis of the patient's electrocardiogram. If a shock is indicated on the basis of the analysis, the shock may be applied through electrodes on the patient's chest. It is desirable to provide a favorable voltage level of the delivered shock to minimize injury to the heart of the patient by avoiding excessive voltage and yet deliver adequate current for successful restoration of circulation.
When the rescuer applies chest compressions to the patient, he/she must supply sufficiently vigorous compression to cause blood to circulate while limiting the force applied to avoid injury to the patient. Apparatus to guide the rescuer would be desirable.